“Several people were seen lying injured and bleeding on the ground, with one of them appearing to be seriously hurt,” read a report in The Guardian. “Poland and Russia fans were also seen fighting and throwing stones outside the stadium.”

Russian fans also reportedly marched to the stadium while waving flags as a way to celebrate Russia Day, which marks the day when the Soviet Union ended. That, of course, did not go over very well with Polish fans, given the two countries’ pasts.

See some of the fighting in the video below. You may want to avoid the video, however, if blood, explosions or awkward sucker punches upset you.

Unsurprisingly, riot police were called on to try to resolve the problem. The police by themselves weren’t enough, so they reportedly used tear gas and nonlethal rounds, according to Deadspin.

Here’s another video, courtesy of Deadspin.

There was also the video below, which features even more brawling in Warsaw. Again, the video isn’t for the faint of heart, especially if you have something against chair throwing.

The Russians are no strangers to reverting to this type of hooliganism, though. The Russian fans were busy stirring up trouble over the weekend, too, with some help from their friends from the Czech Republic. Hooligans on both sides got into it on Saturday, according to the YouTube video below. That melee led UEFA to open “disciplinary proceedings against the Football Union of Russia for the improper conduct of its supporters,” according to Deadspin.